The largest refracting telescope in the world is the 102-cm (40-inch)telescope at Yerkes Observatory,built in 1897.Why have no larger refracting telescopes ever been built?
A) Larger lenses would have too much chromatic aberration.
B) The sagging of larger lenses under their own weight would produce image distortion.
C) The thickness of larger lenses would produce too much spherical aberration.
D) Larger lenses would produce too much magnification.

Question

Quizplus · Accepted Answer

The sagging of larger lenses under their own weight would produce image distortion, which would limit the image quality and decrease the usefulness of the telescope. This issue is particularly problematic for refracting telescopes, which rely on a single large lens, and cannot be easily corrected with additional lenses or mirrors. As a result, most modern telescopes use reflecting designs, where the weight of the mirror is supported from behind and does not cause distortion.

The Largest Refracting Telescope in the World Is the 102-Cm